Filament processing



June 21, 1960 J. L. LOHRKE, JR 2,941,259

FILAMENT PROCESSING Filed Sept. 18, 1956 r lnm\ msms G U IMPULSER INVEN TOR.

JamesL.LohrKe,Jr.

BY MM ATTORNEY FILAMENT PROCESSING James L. Lohrke, Jr., Westtown, Pa. (RD. 5, 'Westchester, Pa.)

Filed Sept. 18, 1956, Ser. No. 610,498

14 Claims. {CL 19-.39)

This invention relates to processing of filaments, concerning especially multiple drawing of continuous filaments composed of organic polymers.

Before manufacture into textile or industrial prod ucts, organic polymeric monofilament and multifilament, referred to generally herein as textile filaments, often are drawn to increased length, a step customarily attended by increased macromolecular orientation along the filamentary axis and consequent tenacity increase and accompanying changes in other physical properties of the drawn filaments. Sometimes more than one drawing operation is performed, as when the manufacturer draws the filaments after their extrusion and solidification and then a subsequent processor redraws them before or during processing of them into fabric.

A primary object of the present invention is novel multiple drawing of textile filaments. An object is improvement in properties of filaments by cyclical drawing and relaxation. A further object is improved conversion of multifilament tow into staple sliver. Other objects of this invention, together with means and methods for attaining the various objects, will be apparent from the following description and the accompanying diagrams.

Fig. l is a diagrammatic block diagram representing practice of the present invention. Fig. 2 is a partially schematized showing of a portion of 'Fig. 1. Fig. 3A is a somewhat schematic elevation of apparatus useful in the practice of this invention and corresponding to the more general showing of Fig. 2; Fig. 3B is a plan of the apparatus of Fig. 3A. Fig. 4A is a similar schematic elevation of further apparatus useful according to the present invention; Fig. 4B is a plan of the apparatus of Fig. 4A. Fig. 5A is a similar elevation of yet other apparatus of the present invention; Fig. 5B is a plan of the apparatus of Fig. 5A. Fig. 6 is an elevation, also schematic, of apparatus corresponding to Fig. 1.

In general, the objects of the present invention are accomplished by subjecting textile filaments to a succession of drawing steps. The invention contemplates particularly, in the drawing of textile filaments to increased length, the improvement comprising running the filaments through a-tensioning zone in which the tension applied to each portion of the filaments varies between a predetermined maximum and a predetermined minimum more than once during their passage through the zone without breaking the filaments. Especially comprehended by this invention is staple sliver produced directly from multifilament tow predrawn on the run through more than one such cycle of alternate tension and relative relaxation before introduction into the conversion zone. Apparatus for attaining these ends is illustrated in the drawings and described below.

Fig.1 shows in block form filamentary band, bundle, or strand 1 being processed according to this invention. Feeding means introduces the filaments into a drawing zone from which they are withdrawn by forwarding means, which in turn introduces them into a conversion zone. There the filaments are converted into sliver 10;

at the end of the zone the resultant sliver comes into contact with drafting means. Located between the two filament-advancing means that flank the drawing zone (i.e., the feeding and forwarding means) is drive means having an impulser, i.e., including mechanism effective to vary the drawing range by varying in cyclic manner the ratio of feeding and forwarding rates and thereby varying the tension to which the filaments are subjected in the drawing zone.

Fig. 2 shows the drive and impulse means broken down into a constant drive and a cyclic drive; accompanying the drive means is double-pole, double-throw switch 2. Pair of rolls 3, 3' and pair of rolls 4, 4' constitute the feeding means and the forwarding means, respectively. The switch has a central contact adapted to apply the constant drive through one of the contacting arms to either the feeding or the forwarding rolls, depending upon which of the two arms is touching that contact, and has two flanking contacts adapted to apply the cyclic drive to the other arm of the switch and, thus, to the filament-advancing rolls at the other end of the drawing zone. The cyclic variation in the rate at which the filaments either are fed into the drawing zone located between the pairs of rolls or are withdrawn from the zone alternately stretches them without breaking and allows them to recover or relax wholly or partly from the stretching or drawing step.

Figs. 3A and 3B show an arrangement of apparatus cor-responding to the setting of the switch in Fig. 2; Fig. 3A represents the various elements in elevation, and Fig. 3B represents the same elements in plan. Drive shaft 14 of roll 4, driven at constant speed by suitable means, not shown, carries circular gear 24 in mesh with similarly shaped gear 26 carried on idler shaft 15. The idler shaft also carries elliptical gear 25 in mesh with elliptical gear 23 mounted on drive shaft 13 of roll 3. It will be apparent that rotation of roll 4 to forward the strand of filaments at a constant rate in the direction indicated by the arrows is accompanied by rotation of roll 3 at a cyclically varying rate, thus providing a ratio of feeding (into the drawing zone) to forwarding (out from the zone) that varies continually between a predetermined maximum and a predetermined minimum as the elliptical gears make each half revolution. This variation alternately stretches or draws the filaments as a group and allows them to relax or recover to shorter length in between times. With the distance between the nips of the respective pairs of rolls exceeding the roll circumference, any given part of each filament is subjected to more than a complete drawing cycle during its passage from the feeding rolls to the forwarding rolls, e.g., being stretched from a relaxed condition, then relaxed, and finally stretched again. Ordinarily the filaments retain part of the increase in length induced during each drawing cycle, and the average surface speed of the forwarding rolls is maintained appreciably above that of the feeding rolls (an overrunning maintained here by apparent choice of the interconnecting circular gears) so as to accommodate (and fix) a net extension or average draw of the filaments.

Another arrangement for varying the in-feeding rate appears in Figs. 4A and 4B, which are schematic representations of the elements in elevation and in correspond ing plan. The feeding and forwarding rolls are attached to the respective roll shafts the same as in Figs. 3A and 3B. Forwarding shaft 14 carries circular gear 34, while similar gear 33 (instead of elliptical gear 23) is mounted on feeding shaft 13. Gear 33 engages idler gear 37 on shaft 17, and it in'turn meshes with gear 38 on shaft 18, which also carries elliptical gear 39. This elliptical gear meshes with elliptical gear 35 mounted on shaft 19; this shaft also carries gear 36, in mesh with gear 34 on the output or forwarding shaft. This arrangement differs from that of Figs. 3A and 3B primarily by relegating the elliptical gears to shafts independent of the roll shafts, an arrangement which not only facilitates wider pas pf e lssthsm lv shl i lsqs nr s st tu of u h gears fo d rsntg is tv r ti it alsopermits variation in therelative sizes of the various circular gears or the rolls themselves, which is conducive to changes in thenumber of drawing cycles to which each filament is subjected, as well as to adjustment of the averagedraw. r

Of course, in each instance the number of shafts interposed between the, shafts of the two yarn-advancing rolls is odd in orderto insure rotation of ,IbOih.lIl the same direction. In both pairs of views the elliptical gears exemplify generally those gear configurations (including, among others, cardioid, oval, square") .that can be employed to provide a cyclic variation in the rate at which the strand of filaments enters the drawing zone (or leaves the'zone, as may be arranged by interchanging the relative positions of the gears), It will be apparent from the diagrams last discussed that the cycle of operations may be performed upon the subject filaments several or many times while any given part of each filament is in the drawing zone.

The frequency and the extent of the drawing cycle also can be controlled readily and with various advantages by means of the apparatus shown in elevation and in plan in Figs. A and 5B. There the advancing shafts, with their attached rolls, appear asin Figs. 4A and 4B; however, pulley 43 is substituted for the gear on the feeding shaft, and there is no gearing or similar linkage connecting the two shafts. The rate of withdrawal of filaments from the drawing zone is fixed by the driving of gear 24 on the forwarding shaft by gear 40 on separate drive.

shaft 44. Above pulley 43 on the input shaft, for which no drive is shown or required, islike pulley 45 afiixed to non-rotatable shaft 46, while belt 41 passes between and about the two pulleys. Located in contact with the outside of the belt, where it is shpported between the pulleys, is eccentric 47 carried on shaft 48, which also carries cycling gear 49. This gear is driven by meshing with drive gear 52 mounted on shaft 51. p

It is readly apparent from Figs. 5A and 5B that as the eccentric rotates to press more firmly against the belt surrounding the pulleys the belt will tighten about them. This tightening imposes drag on roll 3', increasing the tension applied to the filaments in the drawing zone and decreasing the rate of travel of the filaments accordingly. Of course, each complete revolution of the eccentric produces a complete cycle of alternate tightening and slackening of the belt and, consequently, a corresponding cycle of drawing variation in the filaments being processed.

Fig. 6 shows in elevation like pairs of feeding and forwarding rolls with the filaments shown intervening and proceeding onward to be converted by severing and drafting into a sliver of staple fibers the conversion being performed in a manner known in the art (and for that reason, shown only schematically). Likewise, the mechanism for varying the draw of the filaments in the zone between the feeding and forwarding rolls is omitted from this view for clarity, it being understood thatone of the systems shown in the preceding views (or an equivalent) will be employed. From the forwarding rolls the filaments pass between intermeshing ridged'rollersor breaker bars" 61, 62 that act to break the filaments in their passage toward fluted delivery rolls 63 and Belt '64 passes through the nipof the delivery rolls and about roll 63 of the pair and overheadidlerroll 66.

1 The individual filaments no longer are continuous as they leave the belt and the delivery rolls but are in the form discontinuous short lengths of staplefibers; as indicated previously, the aggregate structure composed of filaments in the drawing zone.

the fibers (which itself is continuous) is termed a sliver." Additional rolls 67 and 69 receive sliver 10 and may pass it on to conventional crimping or winding mechanism (not shown). Overrunning of the delivery rolls beyond the surface speed of forwarding rolls 4 and 4', or of final rolls 67 and 69 over the speed of the delivery rolls, drafts the sliver to increased length by causing various of the staple fibers to slide past one another without separating from the sliver. if desired, cyclic variation of draft may be imposed upon the forming or formed sliver by control of tension or speed ofthe delivery rolls or the final rolls (or both) in like manner to that described for the Furthermore, such cyclic drafting variation may be phased so as to oppose or cancel in the sliver some existing unevenness, e.g., nonuniformity in total denier (or other physical characteristic), attributable to the cyclic drawing to which the vmaterial subjected in the earlier part' of the operatio'n. Of course, some or all ofthe pairs ofrolls at the ends of the drawing and drafting zo'nes may be replaced by other gripping means, such assnuhbing rolls located side by sidetfor the strand or sliver to pass over and under, in sequence), as may be desirable to reduce the pp p r Additions or alterations to the described apparatus and procedures may be made without a departure from the present inventive concept. If desired, heat can be applied by any suitable means to raise the temperature in eitheror both the drawing zone and the conversion zone, or subsequent to the conversion zone, for that matter. Elevated temperature is conducive to drawing, as well as to relaxation, of some textile fibers, as is well known; of course, a final separate relaxing operation may bedesirable to stabilize the product length ag'a inst further shrinkage, especially where very high tenacities are not required in the product. Instead of the smoothly varying drawing sequence followed in the equipment described above, an abrupt or square-wave" variation can be imposed upon the filaments being processed, as by means of gears withinterrupted sets of teeth or highly irregular outline. One or more differential gearing arrangements may be employed, as will be apparent, to facilitate change in the cycling ratio. The filaments may be converted into staple by cutting and then be recombined into sliver and then into yarn by the conventional processes of card'- ing, drafting, twisting, etc, as an alternative to the illustrated direct conversion method, although an especial advantage of the present invention is its facilitation of direct conversion of tow into sliver to be spun into staple yarn. Practice of this invention provides staple yarn having softer handle than that made in comparable conventional manner, an advantage carried throughremarkably undiminished to fabrics made from it. Furthermore, repeated drawing according to the invention is beneficial to physical characteristics of textile tow itself, e.g., generally increasing the tenacity without necessarily greatly reducing its elongation to the breaking point, high values ofboth being obviously desirable for threads, twines, and ropes, as well as many fabric end-products. Processing of tow directly into sliver, as described above, also is facilitated by the described cyclic prestretching. A particular benefit of the present invention is production of sliver and yarn composed of staple fibers having finer individual denier than can be processed readily in a system requiring complete severing of the tow bundle into discontinuous lengths and recombination of the staple fibers from a heterogeneous fibrous mass. Furthermore, the increased tenacity of the fibers is especially beneficial where fine yarnsso composed are to be subjected to the appreciable tensions encountered in knitting, weaving, or other modes or fabric manufacture. Additional advantag'es and benefits of the present invention be apparent and will accrue to those undertakingto practice This invention is not limited to use with any particular composition of textile filament but is adapted to processing of known organic compositions generally, including those having cellulosic, polyacrylic, polyamide, polyester, or polyhydrocarbon structures. The invention is expected to prove similarly beneficial to filaments made from organic polymers not now commercial or not even known at this time, perhaps most importantly the thermoplastics among them.

As .an example, a three denier-per-cfilament polyacrylonitrile tow previously drawn to four times its original length was processed on the equipment of Fig. 6 equipped with elliptical gears arranged to give a ninefold draw range (i.e., a ratio of nine times, computed as maximum to minimum of applied draw) and to impose four complete drawing cycles upon every part of each filament during its passage through the drawing zone. A maximum final filament length of 2.5 times the original length (i.e., an average draw of 2.5x) was produced by suitable selection of the interconnecting gears for that amount of overrunning. Processing temperature was 150 C. (dry), and the denier, elongation, and tenacity of the resulting product appear in the following table, along with comparable values for a control subjected to a non-cyclic single-stage draw of 1.7x (a previously practicable maximum on this type of direct conversion equipment), a 1.7 cyclically drawn product (obtained by reducing the overrunning gear ratio), and for the same materials after subsequent relaxation in steam at 10 lbs, gage (a temperature of 115 C.) and attendant reduction in the drawn length.

Although a ninefold draw range and quadruple cycle led to the data in the above table, similar improvement in product characteristics can be obtained under cyclic draw ranges of severalfoldor less and in which the filaments are subjected to as few as two immediately successive stretches and relaxations, respectively. The above data, being merely exemplary, do not necessarily represent conditions of maximum improvement in the stated (or other) properties. Application of the principle of the invention through even wider cyclic drawing ranges and periodicities of increased frequency and different duration will be apparent to those skilled in the art of filament processing.

The claimed invention is:

1. In drawing of orientable textile filaments to increased length without breaking, the improvement comprising runn-ing the filaments in orientable condition through a tensioniug zone in which the tension applied to each portion of the filaments varies between the predetermined maximum and a predetermined minimum more than once during their passage through the zone while maintaining the continuity of the filaments.

2. The process improvement of claim 1, in which the tension applied to the running filaments varies in accordance with a predetermined cycle.

3. In drawing of orientable textile filaments to increased length without breaking, the improvement comprising feeding the filaments in orientable condition at constant rate into a drawing zone and withdrawing them continuously from the zone at a rate varying between a S predetermined maximum and a predetermined minimum more than once while any given part of each filament is in the zone while maintaining the continuity of the filaments.

4. In drawing of orientable textile filaments to increased length without breaking, the improvement comprising feeding the filaments in orientable condition into a drawing zone at a rate varying between a predetermined maximum and a predetermined minimum more than once while any part of each filament is in the zone and withdrawing the filaments from the zone at a constant rate while maintaining the continuity of the filaments.

5. Process of continuously converting a multi filament tow into sliver, comprising passing the tow into and through a drawing zone to increase the length of the filaments, characterized by subjecting each portion of the filaments passing through said zone to more than one cycle of alternate tension and relaxation while maintaining the continuity of the filaments, thereafter passing the tow through a conversion zone and subjecting the filaments to stretch-breaking to convert the tow into sliver.

6. The process of claim 5, in which the sliver is drafted with cyclic variation in suitable phase with respect to the cyclic variation of the drawing to substantially correct any unevenness in the diameter of the finished sliver.

7. In direct conversion of a tow of continuous multifilament into a sliver of staple fibers wherein the tow is advanced continuously, tensioned progressively in portions of length greater than the length of the desired staple fibers, and abruptly deflected intermittently outof the path of advance in order to break the tensioned filaments progressively at the points of deflection, the improvement comprising predrawing the tow through a varying draw cycle more than once before entry into the conversion zone to increase the length of the filaments while maintaining their continuity.

8. Apparatus for producing highly-stretched filaments of increased length comprising means for feeding solidified textile filaments into a drawing zone, means for withdrawing the filaments from the drawing zone, and means for controlling the ratio of feed rate to withdrawal rate of the filaments, including means for varying the ratio cyclically more than once during passage of any given part of each filament through the drawing zone while maintaining the continuity of the filaments.

9. Apparatus comprising means for feeding solidified textile filaments into a drawing zone, means for withdrawing the filaments under tension from the zone, and means for controlling the tension applied to the filaments in the zone, including means for varying the applied tension cyclically more than once during passage of any given pant of each filament through the drawing zone while maintaining the continuity of the filaments.

10. Process of treating solidified textile filaments, comprising supporting the filaments in a predetermined substantially fixed path throughout a zone of constant length and extending the filaments throughout the zone in cyclic manner more than once to increase the length of the filaments while maintaining their continuity.

11. Filamentary product of the treating process of claim 10.

12. Process comprising supporting a given length interval of solidified textile filaments in a substantially fixed path on the run in a drawing zone and cyclically varying, throughout such zone, the actual length of the subject filaments more than once while maintaining constant in extent the end-to-end spacing of the supported length interval and maintaining the continuity of the filaments.

13. Process comprising running orientable textile filaments in orientable condition in a substantially fixed path between a pair of supports maintained a fixed distance apart and cyclically extending the filaments more than once while maintaining them in said fixed path between the supports while maintaining the continuity of the filaments. I

14. In drawing solidified textile filaments or extendthem to increased length to impart increased tenacity thereto, the improvement comprising varying the extension of the filaments more than once in cyclic manner while applying the extensional force to a constant length interval of the filaments and maintaining their continuity.

8 preyius et a1. J n1y 19, 1938 l lamel Dec. 31, 1940 :Iaylop et a]. July 1, ;I9f1l ;Babcock July 7, 195172 Sniith ug. 11 1942 fllng ll July '27, i9 I-Iays et al. Oct. 1;(), 1944 Bjorksten gNov. Z0, 1 945 Lohrke Apr. 22, 1247 Lipscomb Nov. 18, 1952 Preston Mar. 12, 1957 'FGKEI GN "PATENTS 

1. IN DRAWING OF ORIENTABLE TEXTILE FILAMENTS TO INCREASED LENGTH WITHOUT BREAKING, THE IMPROVEMENT COMPRISING RUNNING THE FILAMENTS IN ORIENTABLE CONDITION THROUGH A TEN- 